There were an estimated 1.96 million finishers at U.S. halfs last year, up 6% from 2012's total, and a new record. The charts and table below, created using Running USA's data, highlight some key stats and trends about the half marathon's popularity.

First, the number of finishers in U.S. half marathons has exploded. In 1990, there were an estimated 303,000 finishers. That total had more than doubled by 2004. This year's record total of 1.96 million means that, in just less than a quarter-century, there's been more than a six-fold increase in finishers.

Much of the growth has been driven by increased female participation. In 2013, women made up a record 61% of U.S. half marathon finishers, compared to 53% in 2006. Although the percentage of men finishing half marathons has fallen each of the last several years, the absolute number continues to increase. There were more than 760,000 male finishers of U.S. halfs in 2013, which was more than all finishers in 2006.

The half marathon isn't just a U.S. phenomenon. Although 14 of the 20 largest half marathons in the world in 2013 were U.S. races, the three biggest were overseas. The 45,126 finishers in Goteborg, Sweden was the most in history for an annual half marathon.